1. Technical Field
This present disclosure relates to a cannula useful for penetrating membranes or septums as commonly used in medication vials, intravenous bags, access ports and the like.
2. Description of the Related Art
Many standard containers for pharmaceuticals, medicaments and other substances are air and moisture-tight containers (e.g., vials) having elastomeric stoppers. The container contents are typically accessed by piercing the stopper with a cannulated needle apparatus such as a typical hypodermic needle and syringe. In many applications, the container contents are repeatedly accessed. For example, many injectable pharmaceuticals are packaged in multidose vials requiring a vial access for the withdrawal of each unit dose. Also, many pharmaceuticals are lypholysed in sterile vials for prolonged stability. Such packaging also requires multiple vial entries to reconstitute the contents and withdrawal of the reconstituted contents.
Typically, the elastomeric stoppers are pierced using a sharp metal cannulated needle; usually a needle suitable for intravenous injection. One problem that arises with this type of vial access is coring of the elastomeric stopper. Coring occurs as the vial access needle is urged through the stopper and the needle punches or cuts a small particle of rubber from the stopper. This stopper fragment either drops into the vial or becomes lodged in the cannula and possibly withdrawn into the syringe. In either case, the sterility of the container contents is compromised and, in the latter case, injection of particulate matter into the patient may occur.
The prior art discloses various vial access needles for aspiration of medication including vial access needles providing conically shaped forward tips and fluid dispensing side ports. See, for example, the MONOJECT® Filter Aspiration Needle (1973) manufactured by Sherwood Medical Industries Inc. and U.S. Pat. No. 4,058,121 to Choksi et al., which disclose vial access needles for aspiration of medication.
Therefore, it would be desirable to overcome the disadvantages and drawbacks of the prior art with a vial access cannula that employs structure that minimizes or eliminates coring of elastomeric stoppers. It would also be desirable if the vial access cannula is easily and efficiently manufactured.